Apparatus for inductively heating and quench hardening an elongated workpiece

ABSTRACT

A device for inductively heating and quench hardening an elongated workpiece including a heating station having singleturn inductor extending the length of the workpiece for heating the total workpiece simultaneously and as it is rotated; a quenching station having an elongated quench body for quenching the total workpiece simultaneously and as it is rotated; a movable member at the quenching station for bending the workpiece from one side while the workpiece is being rotated whereby the various portions of the workpiece are alternately flexed between compression and tension; and, means for gradually retracting the member from the workpiece so that the amplitude of flexing is decreased until this amplitude is zero. In this manner, the workpiece is straightened as it is quench hardened.

United States Patent [191 Armstrong 1 June 5, 1973 [54] APPARATUS FORINDUCTIVELY HEATING AND QUENCH HARDENING AN ELONGATED WORKPIECE RelatedUS. Application Data [62] Division of Ser. No. 16,710, March 5, 1970,Pat. No.

[52] US. Cl. ...,.....219/10.67, 2'l9/10.57, 219/1079, 266/4 E [51] Int.Cl. ..H05b 5/00 [58] Field of Search ..219/10.67, 10.69, 219/1057,10.79; 266/4 E, 5 E

[56] References Cited UNITED STATES PATENTS 3,101,165 8/1963 Barkley eta1 ..219/10.79 X

3/1972 Seyfried et a1. ..266/4 E Primary Examiner-E. A. GoldbergAssistant Examiner-B. A. Reynolds Attorney-Meyer, Tilberry and Body [5 7ABSTRACT A device for inductively heating and quench hardening anelongated workpiece including a heating station having single-turninductor extending the length of the workpiece for heating the totalworkpiece simultaneously and as it is rotated; a quenching stationhaving an elongated quench body for quenching the total workpiecesimultaneously and as it is rotated; a movable member at the quenchingstation for bending the workpiece from one side while the workpiece isbeing rotated whereby the various portions of the workpiece arealternately flexed between compression and tension; and, means forgradually retracting the member from the workpiece so that the amplitudeof flexing is decreased until this amplitude is zero. In this manner,the workpiece is straightened as it is quench hardened.

2 Claims, 7 Drawing Figures PATENIED JUN W Mtifia PMENIEUJJN sum summersFIG. 2

APPARATUS FOR INDUCTIVELY HEATING AND QUENCII HARDENING AN ELONGATEDWORKPIECE This is a division of application Ser. No. 16,710 filed Mar.5, 1970, now US. Pat. No. 3,662,995.

This invention relates to the art of induction heating and moreparticularly to a method and apparatus for inductively heating andquench hardening an elongated workpiece. I

The invention is particularly applicable for inductively heating andquench hardening axle shafts having a flange on one end thereof, and itwill be described with reference thereto; however, it will beappreciated that the invention has much broader applications and may beused for inductively heating and quench hardening a variety of elongatedworkpieces.

It has become somewhat common practice to harden the outer surface ofaxle shafts by inductively heating the surface to a temperature abovethe critical temperature of the metal forming the axle shaft and thenquench hardening the shaft. A varietyof apparatus and methods have beendeveloped for accomplishing this function; however, the most commonlyused system includes rotating the axle shaft about a vertical axis andprogressively moving an energized, encircling inductor along the shaft.A quenching unit directly below the inductor quenches the shaftimmediately after it is heated. This type of apparatus was extensivelyused in hardening axle shafts for the automotive industry. It has beenrecently suggested that an increased production for the hardeningapparatus could be provided by inductively heating the complete lengthof an axle shaft simultaneously with a single inductor having twoconductors extending the length of the shaft. By using this type ofapparatus, the quenching arrangement previously used is not appropriate.Consequently, it has been suggested to use a quenching body extendingthe complete length of the shaft for spraying a quenching liquid againstthe previously heated shaft, as it is being rotated. Extensive work isbeing done in developing and improving this type of heating andquenching apparatus.

It has been found that an apparatus for heating and quenching thecomplete length of an axle shaft in single heating and quenchingoperations, accomplished over the complete length of the shaftsimultaneously, may produce an excessive amount of run-out. The presentinvention is directed toward a quenching device for this type ofapparatus which prevents excessive shaft runout and toward the methodperformed by this quenching device.

In accordance with the present invention, there is provided a quenchingdevice for quench hardening an inductively heated, elongated workpiece,having a longitudinal axis extending along its length. This devicecomprises means for rotating the workpiece about the axis, means forspraying a quenching fluid against the workpiece over substantially itscomplete length, a stressing member, means for moving the stressingmember against the workpiece in a direction generally perpendicular tothe axis and to a position bending the rotating workpiece into a concaveconfiguration in this direction, and means for gradually withdrawing themember from the afore-mentioned position and away from the workpiecewhile the workpiece is being rotated and quenched. By utilizing thisapparatus, the quenching operation of the device, which is especiallyadapted for an apparatus wherein the heating operation is performed by asingle turn inductor extending along the total length of the workpiece,minimizes the resulting run-out of the shaft being quench hardened.

In accordance with another aspect of the present invention, there isprovided a method of quenching an elongated heated workpiece having alongitudinal axis. This method comprises the steps of spraying aquenching liquid over the length of the workpiece; simultaneously withthe spraying step, periodically and repeat edly stressing substantiallyall portions of the workpiece between a state of compression and a stateof tension by rotating the workpiece about the axis with respect to itsphysical restraint, the position of which determines the flexingamplitude, and gradually decreasing the flexing amplitude by moving therestraint with respect to the workpiece until the amplitude issubstantially zero.

The primary object of the present invention is the provision of a methodand apparatus for hardening an elongated workpiece, which method andapparatus straightens the workpiece during quench hardening.

Another object of the present invention is the provision of a method andapparatus for hardening an elongated workpiece, which method andapparatus combine a straightening operation with a quench hardeningprocess.

Yet another object of the present invention is the provision of a methodand apparatus of hardening an elongated workpiece, which method andapparatus uses a coil to inductively heat the total workpiece while thecoil is stationary, a quench body for quenching the total workpiecewhile the body is stationary, and a movable stressing member fortransversely flexing the workpiece with gradual decreasing amplitude forstraightening the workpiece.

These and other objects and advantages will become apparent from thefollowing description taken together with the accompanying drawings, inwhich:

FIG. 1 is a side elevational view showing, somewhat schematically, anapparatus utilizing the present invention;

FIG. 2 is a cross-sectional view taken generally along line 2-2 of FIG.1;

FIG. 2a is an enlarged view showing a certain aspect of the apparatusillustrated in FIGS. 1 and 2;

FIG. 2b is a schematic view illustrating a slight modification of theapparatus illustrated in FIGS. 1 and 2;

FIG. 3 is an enlarged view taken generally along line 3-3 of FIG. 2;

FIG. 4 is a cross-sectional view taken generally alon line 4-4 of FIG.3; and,

FIG. 5 is a partial cross-sectional view taken generally along line 55of FIG. 4.

Referring now to the drawings, wherein the showings are for the purposeof illustrating a preferred embodiment of the invention only and not forthe purpose of I limiting same, FIGS. 1 and 2 show an apparatus A for Bis loaded onto the turret 20 at loading device 22, turret 20 is indexedto bring the workpiece to the induction heating station 24. At thisstation, the workpiece is inductively heated, and it is then indexed tothe quench hardening station 26 where the workpiece is hardened andstraightened in accordance with the present invention. Thereafter, theworkpiece is indexed by the turret 20 to the unloading station 28 whereit is removed and deposited onto a chain conveyor 30 for movement fromthe apparatus A.

Referring now to the turret 20, a variety of structures could beutilized for moving the workpiece from station-to-station; however, inaccordance with the illustrated embodiment of the invention, turret 20includes a center shaft 40 indexed by an indexing mechanism 42 whichincludes a drive motor 44 and an indexing gear box 46. The axle shafts Bare supported by the turret in a manner so that they may be rotated. Avariety of structures could be used to accomplish this purpose; I

however, in the illustrated embodiment, stationary abutments 50 areprovided with either an upper V- shape support structure or a set ofrollers, as shown. These abutments, or rests, contact the end of theworkpiece opposite flange 12 and are spaced about the turret every 90.Of course, any number of stations could be provided in apparatus A, inwhich case a corresponding number of abutments or rests 50 could beemployed. Adjacent the flange 12, there is provided a rotatably drivenflange clamp 60 which is rotated by a mechanism carried by the turret,which mechanism is illustrated as drive motors 62. Clamping fingers 64on the flange clamp are operated by fluid introduced into an operatingcylinder 66 having an input hydraulic line 68 connected throughappropriate conduits and valves to a hydraulic inlet supply line 70,which is stationary and employs a swivel connection or coupling (notshown). Fluid pressure introduced through inlet 70 is controlled byappropriate valving, not shown, to selectively operate the particularflange clamp to clamp or release an axle shaft from the turret 20. Acenter 72 is employed by the flange clamp to locate the workpiece withrespect to its axis, and an abutment 74 is used as a reaction memberagainst which the fingers 64 pull the centered flange 12 to lock it ontothe rotatable flange clamp.

Referring now to the loading device 22, this device, as illustrated,includes two spaced pivoted arms 80, 82 having upwardly facing nests 84and movable by an operating cylinder 86 between the phantom lineposition and the solid line position, as shown in FIG. 2. After a shafthas been located in the solid line position shown in FIG. 2, cylinder orpusher rod 88, shown in FIG. 1, moves the shaft B to the right againstthe center 72. Thereafter, finger 64 clamps the flange 12 againstabutmentor abutments 74. The left end of the shaft is positionedadjacent to and overlies abutment 50. Manually adjustable rods or bars90 are used to locate the arms 80, 82 to accept workpieces havingvarious lengths. The operation of the loading device 22 is quiteapparent from the above description. The workpiece is placed into thenests 84, in the phantom line position of FIG. 2. The-arms 80, 82 arepivoted to bring the workpiece into alignment'with center 72.Thereafter, push rod 88 forces the shaft into the flange clamp and thefingers clamp the flange. There is no assurance that the shaft willcontact the rest 50; however, the function of the rest becomes importantin other stations of the apparatus A.

After being loaded, the shaft is moved by the turret 20 to the heatingstation 24, best shown in FIG. 2. A power supply is movable in avertical direction on guide pins 102 by a cylinder 104. In this manner,an inductor may be moved between the solid line and the phantom linepositions shown in FIG. 2. Inductor 110 includes parallel conductors112, 114 which extend substantially the total length of the cylindricalportion 10 of the workpiece and are connected at their respective endsby arcuate connecting legs or conductors 1 16, 118. One of the parallelconductors is parted and joined to input leads 120, 122, which areelectrically connected with the output of power supply 100. During theheating operation, workpiece B is rotated by the flange clamp 60 uponactuation of motor 62. To assure that the workpiece rotates in acontrolled manner and that distorted workpieces will not contact theconductor 110, an arrangement is provided for physically forcing thenon-flanged end of axle shaft B against rest 50. A variety of structurescould be used for this purpose; however, a schematic representation ofone of these structures is illustrated in FIG. 2a. In accordance withthis embodiment, abutments I30, 132, which may be V-shaped or have a setof rollers, are supported onto a frame 134 so that abutment contacts theshaft B adjacent rest 50 and abutment 132 contacts the shaft generallyat its mid-point. In this manner, the abutments hold shaft B against therest 50 while it is rotated by the flange clamp 60. The abutments 130 or132 could be individually operated or spring biased to move separately.They can be connected onto the input lead 120 or to another structuremovable with or at the same time as the power supply 100. The abutmentsalso maintain proper minimum spacing between the inductor and theworkpiece.

In operation of the heating station 24, the inductor 110 is raised bythe power supply 100 before a workpiece is moved into the heatingstation. Thereafter, the inductor 110 is shifted downwardly to form amagnetic coupling between the conductors and the cylindrical bodyportion 10. In this position, the power supply is energized and motor 62rotates the axle shaft. The abutments 130, 132 maintain the axle shaftin alignment. The heating is effected simultaneously over the length ofthe workpiece. In some instances, the conductor cannot be moved solelyin a vertical direction because conductor 118 may interfere with theclamping fingers 64 if the conductor is to be spaced closely adjacentflange 12. To overcome this difficulty, it is within the contemplationof the present invention to move the inductor at an angle with respectto the axis of the workpiece. This arrangement is schematicallyillustrated in FIG. 2b wherein the power supply 100 and the inductor 110are moved along an angled path a from an up position to a down position.Of course, other angled paths could be used to allow close coupling ofthe inductor 118 with respect to the flange 12 without interference withfingers 64. I

The present invention primarily relates to the quench hardening station26, the structure of which is best illustrated in FIGS. 3-5. Inaccordance with the preferred embodiment of the present invention, thequench station includes a C-shaped quench body having a longitudinallyextending, workpiece clearance opening 142. The length of the quenchbody generally corresponds with the heated length of the cylindricalbody portion 10. The quench body includes an internal liquid passage 146terminating in a plurality of aperture means or holes 148 through whichthe quenching liquid is sprayed against a workpiece B as it is rotatedby motor 62. A liquid inlet means 150 directs quenching liquid to theinternal passage 146. The quench body is secured onto supports 152which, in turn, are connected to guide rods 154, 156 slidably receivedwithin bushings 160, 162. An operating arm 164 powered by a pneumatic orhydraulic cylinder 166 moves the quench body toward and away from theworkpiece B.

In operation, the cylinder 166 retracts the quench body 140 before aworkpiece is moved into or away from the quench station. With the quenchbody retracted, a heated workpiece B is indexed by turret 20 to thequench station. Cylinder 166 then shifts the quench body to the positionillustrated in FIGS. 3 and 4. By an appropriate control, the heatedworkpiece is rotated about its axis and liquid is sprayed thereonthrough holes 148. In this manner, the complete length of the workpieceis quenched hardened simultaneously. In accordance with the invention,during the quench hardening operation, the cylindrical portion isstraight-- ened by the mechanism similar to that illustrated in my priorUS. Pat. No. 3,213,659. This mechanism, as illustrated, includes aworkpiece stressing member 170 terminating in spaced rollers 172, 174and movable in a controlled manner by a drive arrangement, schematicallyillustrated as a power cylinder 176.

In operation of the straightening mechanism, the member 170 is forcedinto the rotating workpiece B with a force sufficient to plasticallydeform the workpiece as it is being quench hardened. In this manner, theactual axis b of the workpiece is forced beyond the neutral or desiredaxis 0 of the workpiece. As the workpiece is rotated, the variousportions of the cylindrical portion are periodically and repeatedlytensioned and compressed by flexing the shaft with stressing member 170.Thereafter, the stressing member 170 is gradually withdrawn from theworkpiece. This reduces the flexing amplitude defined by the differencebetween axes b and c. When the cylindrical portion 10 becomes straightand the actual axis b corresponds with the neutral axis c, furtherretraction of the stressing member withdraws the stressing member fromthe workpiece. This leaves the workpiece substantially straightenedduring the quench hardening operation. No subsequent straightening isrequired. This simultaneous quenching and straightening of the workpieceinduces straightening while austenitic field is being transformed tomartensite. This provides an improved surface strength for theworkpiece.

After shaft B is quench hardened and straightened, the workpiece isindexed to the unloading station 28, best shown in FIG. 2, where spacedarms 180, 182 are pivotally mounted onto the apparatus A and haveupwardly facing nests 184. The cylinder 186 shifts the arms 180, 182between the phantom line position and the solid line position shown inFIG. 2. In the solid line position, the chain conveyor 30 picks off thehardened and straightened shafts by any appropriate mechanism. Inaccordance with the illustrated embodiment, conveyor 30 includes spaceddriven chains 190, 192 including a plurality of spaced pick-up plates orstations 194. The operation of the conveyor 30 is apparent from thedrawings and the above description.

For simplicity, the necessary hydraulic and electrical controls are notillustrated. Various arrangements could be utilized for accomplishingthe functions which are to be performed by the apparatus A.

Having thus described my invention, I claim:

1. In an apparatus for inductively heating an elongated workpiece havinga cylindrical body portion with first and second ends and a central,longitudinally extending axis and a flange adjacent said first end ofsaid body portion, said apparatus comprising means for clamping saidflange end of said workpiece; means for rotatably supporting said secondend of said workpiece; means for rotating said workpiece by said clampedflanged end about said axis; an inductor with two generally parallelconductors extending parallel to said axis and over substantially thelength of said cylindrical body portion between said first and secondends; power means for energizing said inductor; and, means for shiftingsaid inductor between a remote, non-heating position and a heatingposition adjacent to and spaced slightly from said cylindrical portion,the improvement comprising: said rotatable supporting means comprising agenerally fixed abutment means for contacting said body portion adjacentsaid second end and generally on the opposite side of said axis fromsaid inductor, said abutment having a support means for contacting saidbody portion at least at two circumferentially spaced positions, andmeans for selectively forcing said cylindrical body portion into saidsupport means at least while said inductor is in said heating position.

2. The improvement as defined in claim 1 wherein said forcing meansincludes an abutment means movable with said inductor.

1. In an apparatus for inductively heating an elongated workpiece havinga cylindrical body portion with first and second ends and a central,longitudinally extending axis and a flange adjacent said first end ofsaid body portion, said apparatus comprising means for clamping saidflange end of said workpiece; means for rotatably supporting said secondend of said workpiece; means for rotating said workpiece by said clampedflanged end about said axis; an inductor with two generally parallelconductors extending parallel to said axis and over substantially thelength of said cylindrical body portion between said first and secondends; power means for energizing said inductor; and, means for shiftingsaid inductor between a remote, non-heating position and a heatingposition adjacent to and spaced slightly from said cylindrical portion,the improvement comprising: said rotatable Supporting means comprising agenerally fixed abutment means for contacting said body portion adjacentsaid second end and generally on the opposite side of said axis fromsaid inductor, said abutment having a support means for contacting saidbody portion at least at two circumferentially spaced positions, andmeans for selectively forcing said cylindrical body portion into saidsupport means at least while said inductor is in said heating position.2. The improvement as defined in claim 1 wherein said forcing meansincludes an abutment means movable with said inductor.